String musical instrument with chord tuning mechanism



Jan. 4, 1949. J. D. HARLIN 1 2,458,263

STRING MUSICAL INSTRUMENT WITH CHORD TUNING MECHANISM Filed Aug. 21, 1947 5 Sheets-Sheet 1 aid 2 J. D. HARLIN STRING MUSICAL INSTRU Jan. 4, 1949.

MENT WITH CHORD TUNII' G MECHANISM 5 Sheets-Sheet 2 Filed Aug. 21, 1947 lax EAVAAA I \l iivlll 1|1|| L Jan. 4, 1949.

Filed Aug. 21, 1947 J. D. HARLIN STRING MUSICAL INSTRUMENT WITH CHORD TUNING MECHANISM 3 Sheets-Sheet 3 Patented Jan. 4, 1949 STRING MUSICAL INSTRUMENT WITH CHORD TUNING MECHANISM J. D. Harlin, Indianapolis, Ind., assignor to Harlin Brothers, Indianapolis, Ind., a partnership Application August 21, 1947, Serial No. 769,922

13 Claims. 1

This invention relates to string musical instruments and pertains more especially, although not exclusively, to such instruments as the guitar, mandolin, banjo and the like, which are played by picking or stroking the strings.

The primary object of my invention is to provide a stringed instrument on which one or more or several chords can be played Without resort to diflicult fingering operations which can other- Wise be performed, if at all, only by skilled performers, thus making it possible for players having only rudimentary skill to give performances comparable to the performances of players of much greater experience and accomplishment.

To the above end I have devised a stringed instrument which is provided with one or more, usually several, sets of mechanisms each of which is adapted to be separately foot-actuated to vary the tension of the several strings or pre-selected ones thereof in such manner that when the several strings are stroked a definite predetermined chord is produced, no musical skill being required to play any chord the instrument has previously been set to produce.

My invention contemplates the addition to an otherwise more or less conventional stringed instrument of one or more mechanisms, each of which may be individually adjusted, as by means of adjustable actuating screws or the like, so that when it is brought into action, as, for example, by depressing a foot pedal individual thereto, certain strings of the instrument are consequently tightened while others may be slackened, or all may be tightened or all slackened, as the case may be; or certain strings may be tightened, others slackened and still others unchanged from their normal tension, depending entirely upon the make-up of the chord which it is desired to produce.

My invention contemplates any mechanism which is operative in response to a common actuating member simultaneously to alter the tension of a plurality of strings in such manner that the tension of certain strings is increased while that of other strings is decreased. But in its specific and more limited aspects my invention is characterized by the provision of a pivoted element or rocker for each string, to one and of which, individually, each string is anchored, and which functions upon rotation about a pivotal center either to tighten or loosen its attached string in conformity with the manner of its operation or direction of movement. To actuate the aforementioned pivoted element or rocker there are provided, in each instance, two operating levers constituting a pair, of which there is one pair for each rocker, the levers of each pair being effective, conjointly, upon actuation, to tighten their respective strings, whereas one lever of each pair,'when operated individually, is effective to cause a rotation of the associated rocker in a direction to slacken the tension of the attached string. By virtue of this arrangement it is possible selectively to vary the tension of the strings so that certain strings are tightened while others are slackened, all in response to a single operation of a common actuating member, such, for example, as a foot pedal.

Another novel feature of my invention lies in the means which I have devised for actuating the several pairs of levers in unison so that the tension of a plurality of strings can be varied simultaneously in accordance with a preconceived plan. This feature is characterized by the provision of a cross-bar which overlies and extends transversely of the several pairs of levers .of a given set and carries a plurality of pairs of lever-actuating screws which are individually adjustable, one screw of each pair being capable, when suitably adjusted, or depressing both of a given pair of levers while the other screw of said pair is capable of depressing only one lever of the said pair. By selectively adjusting said screws the player can set the instrument for the playing of any desired chord or, alternatively, the adjusting of said screws can be carried out by the instrument manufacturer.

Additional objects and novel features of this invention will be apparent from the ensuing detailed description.

In the accompanying drawings (3 sheets) I have illustrated, by way of example, an application of my instrument to a stringed musical instrument of special design, the musical output of which is similar to that of a guitar.

Referring to the drawings:

Fig. 1 is a plan view of the instrument;

Fig. 2 is a side elevational view of the same;

Fig. 3 is a fragmentary sectional view taken at line 3-3 of Fig. 2;

Fig. 4 is an enlarged longitudinal sectional view taken at line 4-4 of Fig. 1;

Fig. 5 is a fragmentary plan view of the string tension adjusting mechanism;

Fig. 6 is an elevational view, partly in section, taken at line 6-6 of Fig. 4;

Fig, '1 is a sectional view taken at line 1-1 of Fig. 5;

Fig. 8 is a sub-assembly detail view of a part of the mechanism which serves to vary the ten- "of which one'is provided'for each I picted in Figs.

rocker member and swaged e 1 fo ec r n the j'dra'wal through said aperture. her, while "serving" as an anchorage for one end of its attached stringalsofun'ctions through 'appropriatemanipulation to alter thetension 'of its string in the manner hereinafterdescribed.

sion of one of the strings of the instrument preparatorily to the playing of a chord, this view serving to illustrate the manner in which the tension of a string is slackened for the purpose of lowering its pitch;

Fig. 9 is a view similar to Fig. 8 illustrating the manner in, which the tension ofa string is increased by depressin both of twoleversjgwh'ich function conjointly to regulate the string tension;

Fig. 10 is a perspective view of a spring-tensioning lever with a rocker pivotally attached thereto;

Fig. 11 is a perspective view of area ringtensionin lever which, in combination 'with"the lever of Fig. 10. forms a co-operating pair, there 15 being one such pair of levers for eachstringrhd Fig. 12 is a fragmentaryperspective 'view of the base member of one of "the'rollereciuipped bridges of the instrument. y The instrument illustrated comprises a sounding board I of rectangular configuration, as de pict'ed in Fig.1, which is supported irdmjt he iioor bynineans of. four legs+one at A each corner identified, each, by jrefer encenumeral II, The

'height of 'the'sounding board above the floorlevel is usually suchasjto suit the convenience of a player sitting alongside the instrument. Butit may, on the other handfbe high enough to accommodatea standing player. Six musicalistrin'gs, v of the sounding board, overlying the sameand spaced thereabove; and ,these rest on two'bridges I3 and M which, in turn,"are'securedtothe sounding board. I

The 'left-hand'end offeach string I2, 'asj'viewed in Figs. 1 "andf'Z, is attached t'o'a tuning key I5, string said keys bein of the type ordinarily provided on guitars and other stringed instruments The strings I2 Jare tuned'in the'convention'al manner by'turning keys I5.

V The right-hand end'of eac string I2,as del and 2,"is anchored to an'individual rocker member I IGTeach strin .bejing passed through an aperture. I6a in its'asso'ciated 'to 'form an enlargesarnea ainst "with- Ea'ch rocker mem- As shown most clearly in Figs. 8'-'l0, incl usive,

v the rocker members I16, each consist of arectangular metal plate I6b having an-integral'lug I60.

which has a depending tailpiece'lfid. The latter is separated from the adjacent face of plate I6b to form a slot I6e.

clockwise direction, as viewed in Fig, 8, will causea slackening of the tensio I2.

A second lever I9, shown in"prspectiveiinfFig. 11, is mounted immediatelyadjacent andlat the far side of each lever The'leversyIiI'an'd I9 as combined in co-operating pairs; of which there I2 arestretcjed "lengthwise 4o 'fa' s g J its ee m =45 fp res si'nglever I'8Vonly, since lever pin I1 to ,the short vertical arm v I8, which comprises, in

fingers between'which the lug.

n of the attached string are six in this instance, one for each string. Levers I8 and I9 are provided with holes 20 and 2|, respectively, by means of which they are mounted on a pin 22 which extends transversely 5 of the strings I2 and is suitably supported at its two ends. Lever; I9 hasan upstanding arm I9a to Which "is js ecuredfla horizontal pin"23 which projects into and fits within slot I6e. Said pin 23 bears against tailpiece id and serves to anchor rocker member "I6 against counterclockwise rotation under the fte 'sio'nfpifiits s'tring I2, except when lever I 9 is *purpo's ly depressed as presently will be explained. Lever I9 isv provided with a horizontally profjjectin'g -i'ntlegraljlug'I9b which underlies and normally contacts the right-hand end of lever I8. 'An'otch "IB'c is cut in lever I8 to clear lug I9b, thereby allowin the upper surfaces of the hori- -'z'ontal arms of the two levers normally to lie flushwith each other or apprOXimately so. jIn FigQB the rocker member I6 and two assoat'd levers I B an'dQIS are shown in full linesin err normal positions, wherein the normal ten- "sionis applie to 'string I2,. But in the same .fi l e lever I19jijs shown in" dotted outline in a .fdcpressed position, leverQI8 remaining in its norjinal posture, "The depressio n'of lever I9 causes pin] 23 'to move clockwise in an arcuate path 'abgo'ut pin 22, thereby causing-a counterclockwise rotation oi rocker member I6 to the posture jtirereoi-inwhich'it is depicted in dotted outline. ;This, 'obviously, results in slackening the tension on strin I2. ii'ssumirigla controlled and appropria te "degreerofi slackening of string tension, it will be apparent that the pitch of the string can thus belowered t0 'apiedetermined value, which "may be'a sub-harmonic of the normal pitch. In Fig.9 the full line showing of the two levers fis hefsame as'th'at bf Fig.8, the rocker member posture, with consequent aljtensionon string I2. Butthe dotted out- Fig.f9 .is inten'ded to illustrate the result pressingboth levers "I'8'and I9 simultaneously this being accomplished by directly de- I I9 is mechanjic ailyf'coupledjtq lever I8 by virtue of lug I 9b -iwlii'ch underlies "the end'portionoflever I8. It willbe'fs'een that when the'two leversI8 and IQ .of fagiven. pair-"are jointly depressed, as illus- 501 t'ratjed Fig. 9, the associated'pin 23 remains ,in'normal"positionalrelation to pins I1 and 22 'a'ri 1' that rocker membrIB consequently refvolves bodily'about 'pin22 in the clockwise direc- 'ri nan'q us'mcreases thelt'ensio-n on string I2. Thesix'p'airsoi levers, each comprising a lever f"and"a"le'ver iegaie disposed 'in a common hor- 'izontal planejas best: depicted in Fig. 6,'andare "spaced apart 'incohformity fwith the'spac'ing of strings I 2. Spacing pins 24- serve to' maintain the '60 properispacing betweenad'jacentipairs of levers.

, E ach,lever I 9' rests on" an: individual coil spring 25 and'jis'centered in the top of'its spring'my ginaris ofia boss I which proiects'downwardly fr' m'its rr'e ead. The" springs25 serve to" hold sfI9 in theirriorinal postures and thus to ss p'i'ris" 23 against the'tailpieces I6d, thereby ounte racthig the tension of strings l2. At the ffsahie timefandby'virtue of the fact that the free lends of fle' vers I 8 rest on the lugs I91), springs 25 7 flf'al'so press upwardly against thesaidfree ends of 'jlversf I 8.:a'nd" serve to hold the latter'in normal 'posture'whenever the strings I2 may be loosened ordet'ached 5 I I a I if Tl'ie tens'ion pr strings I 2. is transmitted 7 through rocker members I6'to the vertical lever arms 18a and thence to the abutment plate 26, as depicted most clearly in Fig. 4.

There are shown in the drawings two cross-bars 21 and 28 overlying and extending transversely of the several pairs of levers l8 and I9. These crossbars are vertically slidable bodily on guide pins 29 and 30, and each is supported upon and pressed upwardly by a pair of coil springs 3| and 32 through which pass a pair of draw rods 33, 34, which are attached at their upper ends to the cross-bars and threaded at their lower ends to receive yokes 35, the latter being secured to their respective draw rods by means of nuts 36, which facilitate vertical adjustments of the yokes.

Pivotally connected to each yoke 35 is a connecting rod 31, each of which is connected through a turnbuckle 38 to an individual foot pedal 39 and 40. Depressing either of the foot pedals causes a downward movement of the corresponding cross-bar against the pressure of springs 31 and 32. The maximum downward movement of a cross-bar is reached when it strikes the two side plates 4|, as will be evident from an inspection of Fig. 6.

Each cross-bar is drilled and tapped to receive six pairs of actuating screws 42, each said pair consisting of one screw which is adapted to engage the top surface of a lever IB and one screw which is adapted to engage the top surface of a lever is. These screws are designed to be indie vidually adjustable so that one or the other of each pair is efiective to engage and depress its associated lever. A downward adjustment of only the left-hand screw of any pair, as viewed in Fig. 6, will cause the corresponding lever Hi to be engaged and depressed when the supporting crossbar descends. This, of course, results in rotating both levers l8 and I9 about pin 22, because the free end of each lever I9 is coupled through its lug I91) with the associated lever I8. The outcome, as previously explained, is a tightening of the string connected to the actuated pair of levers, On the other hand, a downward adjustment of only the right-hand screw of any pair, as viewed in Fig. 6, will cause the corresponding lever 19 to be engaged and depressed when the cross-bar descends. In such case the associated lever 18 remains in normal posture because the coupling effected by lug lllb is not such as to cause lever [B to follow lever l9, although the converse is true. As previously explained, a depression of lever l9 results in slackening the tension of the associated string.

In adjusting the instrument to play a proposed chord, the player or tuner depresses one of the pedals until the corresponding cross-bar reaches bottomthe actuating screws having usually first been backed off so that none of them touches its associated lever, and the instrument having been tuned in the usual manner of tuning stringed instruments, that is by means of keys l5. Then certain of the actuating screws 42, depending upon which strings require additional tensioning or slackening, are adjusted downwardly, one at a time, in conformity with the pitch changes needed in order to condition the instrument for playing the proposed chord.

The actuating screws carried by each cross-bar are thus adjusted to condition the instrument for a particular chord; and there may be provided as many cross-bars and actuating pedals as desired, within the limits of available space.

Although the instrument illustrated is shown equipped to be conditioned to play only two chords, I prefer usually to provide for the playing of a larger number of chords, generally six. The means for doing so consists of six cross-bars and six pedals.

The above-described instrument may be and preferably is provided with a magnetic pick-up 45 by virtue of which the volume of musical output can be stepped up through the medium of an electrical amplifier.

Another feature of my invention resides in the two bridges l3 and i4. These each comprise a base member 46 secured to the sounding board and functioning, in each instance, as a support for a rod 48 on which are rotatably mounted six rollers 49, each of which is grooved peripherally to seat one of the strings l2. Said rollers rotate slightly on rods 48 as the strings resting thereon stretch and slacken, thus eliminating or greatly reducing abrasion of the strings and the contacting bridge surfaces, and the life expectancy of the strings is, in consequence, materially increased. In Fig. 12 there is shown a perspective view of one of the base members 46 which, it will be seen, is milled to form a plurality of slots 41 for the reception and positioning of rollers 49.

-' Said base members are also milled to form, in

each case, a longitudinal slot 41a for reception of the associated rod 48.

It is thought to be self-evident to those skilled in the art that there are many possible modifications and alternatives within the scope and purview of my broad inventive concept and, accordingly, I do not wish to be limited otherwise than as clearly indicated by the terms of the appended claims.

Having described my invention what I claim and wish to secure by Letters Patent is:

l. The combination in a musical instrument, of a group of laterally spaced strings, means for anchoring each of said strings at one end of the group, a plurality of rocker members, one for each of said strings individually, each of said rocker members being attached to its individual string and effective upon being rocked in one direction to increase the tension of its string and, upon being rocked in the opposite direction, to slacken the tension of its string, a crossbar associated with said rocker members conjointly, and means including a. plurality of pairs of actuating screws for actuating said rocker members in response to a movement of said crossbar, said pairs of screws being individually associated with said rocker members, one screw of each pair being effective, when suitably adjusted, to cause a movement of its associated rocker member in a direction to increase the tension of its attached string, the other screw of each pair being effective, when suitably adjusted, to cause a movement of its associated rocker member in a direction to slacken the tension or" its attached string.

2. The combination in a musical instrument, of a group of laterally spaced strings, means for anchoring each of said strings at one end of the group, and a plurality of tuning units, one for each string, each said tuning unit including a rocker member together with a first lever and a second lever, said rocker member being attached to one of said strings and operative alternatively to increase and decrease the tension thereof in accordance with the direction of its movement. said rocker member being pivotally mounted upon and carried by said first lever, said second lever being normally operative, conjointly with said first lever, to lock said rocker member in its normal posture wherein it maintains normal tension &585363 onjts string, said second leverkbeing operative, upon being moved from its normal'posture independently of said first lever to relax its holdon said rockermember-and thereby allowsaidrocker member to. rotate in a direction to slacken thatension of its string, said first and-second levers being, effective, upon conjoint movement-, to move said rocker member in;a direction jto ine crease the tension of its. string;

3;, The combination in a musical instrument, of a group of laterally spaced strings, means for anchoring each of said strings at one end of the group, aplurality of tuning units, onefor each string,;each said tuning unit including a rocker member together with a first lever and asecond lever, saidrocker member being attached-to one of; said strings and operative alternatively to increase-and slacken the tension thereofin accordance with the direction of its movement, said rocker :member being pivotally mounted upon and carried'by said first lever, said second lever being normally efiective, conjointly with saidfirst lever, to lock said rocker member. ina normal, posture wherein it maintainsv a normal tension on itsstring, said second lever beingoperative, upon being rotated out of its normal posture independently of said first lever to relax itshold on said rocker member and thereby allowsa-id rocker member to move in a direction to slacken the tension of its string, said first and second levers being effective, upon conjoint rotationin agiven direction tomove saidrocker member in a direction to increase the tension of its string, and means operative to actuatesaid tuning units simultaneously, said last-mentioned means including a manually movable member and a plurality of pairs of actuating elements, one pair for each tuning unit, one element of each pair being operative, when suitably adjusted, to rotate both said levers conjointly and thereby increase the tension of the related string, the other element of each pair being operative, when suitably adjusted, to rotate said second lever onlyand thereby slacken the tension of said string, said elements being movable simultaneously by said manually movable member.

4. The combination in a musical instrument, of a group of laterally spaced strings, means for anchoring each of said strings at one end of the group, a plurality of tuning units, one for each string, each said tuning unit includinga rocker member together with a first lever and a second lever, said rocker member being attached'to one of said strings and operative alternately to increase and slacken the tension thereof in accordance with the direction of its movement, said rocker member being pivotally mounted upon and carried by, said first lever, said second lever being normally effective, conjointly with said first lever, to lock said rocker member in a normal posture wherein it maintains a normal tension on its string, said second lever being operative, upon being rotated in a given direction out. of its normal posture independently of said first lever to relax its hold. on said rocker member and thereby allow said rocker member to rotatein a direction to slacken the tension of its string, said first and second levers being efiective, upon conjoint rotation. in a given direction to move said rocker member in a direction to increase the tension of its string, and means operative to actuate said tuning units simultaneously whereby to tighten certain of said strings and slacken other of said strings, said last-mentioned means includinga cross-bar extending transversely" of saidtuning units :and manually movable bodily toward and away fr0m= said tuning; units,-- and la plurality-of pairs. of actuating screws carried by said-crossebar, one pair for each tuning unit, one-said screw of each pair being operative in response. toa movement of said cross-bar to rotate both levers of its-associated tuningunit. inra direction toincreasethe tension of the associated string, the other screw of each pair being opera; tive in responseto a like movementof said crossbar, to rotate only the second lever of itsassoelatedv tuning, unit in a direction to slacken the tension: of the associated string.

5. The combination in a: musical instrument, of a group; of laterally spaced stringsandmanually operable means efiective through arsingle movementsimultaneously totighten certain :of said strings and to slacken certain others ofv said strings,;said means including a plurality of pairs of actuating elements, onepair for each string individually, the two elements of each pair being independently;adjustable so that, only one or the other is effective, one element of each pair, being efiective, when suitably adjusted, to cause a tightening of the associated string. in response to an actuation ofgsaid manually operable means, the otherelement. of each pair being eifective, when suitably adjusted, to cause a' slackening of its associated string in response to an actuation: of

said; manually operable means.

6; T-he combination in a musical instrument, ofagroup of laterally spaced strings, andmanua-lly operable means eiiective through a single movement simultaneously to tighten certain of said-strings and to slacken certain others of said strings, said means including a manually movable bar and; a plurality'of pairs of actuating screws carried bysaid-bar and movable therewith, 'each pair of; screws being operatively associated with one of; said strings, one screw of each pair being eifective; when suitably adjusted, to cause a tightening of; its associated string in response to a movement: of said bar, the other screw of each pair; being: effective, when suitably adjusted; to causeaslackening of its associated string.

'7. A; tuning unit for a stringed musical instrue mentx:comprising,: a first lever constituting; a bellcrank'having a short lever arm and a long lever arm,,a rocker member pivotally mounted on'saidshort leverarm and adapted at one end for anchoring attachment. to a musical string, a secondllever having means engaginglsaid rocker member and efiective when said second lever is in normal posture to hold said rocker member against rotation under. the tension of its attached string, an'd spring means normally holding both saidlevers in. normal posture, the arrangement beingisuch that-when both said levers are rotated away, from normal posture in a given. direction againstsaid' spring means the tension of the attachedstrin'g. is increased, said tension being decreased when said second lever only is rotated away from normal-posture in said given direction.

8. A tuning unitfor a stringed'musical instrument com-prising: a first lever constituting a bellcranla'h'aving a short lever arm and a long lever arm, a rocker member pivotally mounted on said short-lever arm and adapted at one end for anchoring attachmentto a musical string, a second' lever 'fulcrumed co-aXially with said first lever, said: second lever being disposed immediately adjacent-said first lever and having an arm which is normally co-extensive lineally with the long arm of said firstlever, said secondilever shaving means engaging said rocker'membenand efiective when said second lever is in normal posture to hold said rocker member against rotation under the tension of its attached string, and spring means normally holding both said levers in normal posture, the arrangement being such that when both said levers are rotated about their common. fulcrum away from normal posture in a given direction against said spring means the tension of the attached string is increased, said tension being decreased when said second lever only is rotated away from normal posture in said given direction about said common fulcrum.

9. A tuning unit for a stringed musical instrument comprising: a first lever and a second lever having a common pivotal center, a rocker member pivotally mounted on and carried by said first lever, said rocker member being adapted for attachment to one end of a musical string, a pin carried by said second lever and engaging said rocker member and effective when said levers are in normal posture to hold said rocker member against rotation under the tension of the attached string, said levers normally extending in parallel side-by-side relation from their common pivotal center, and spring means normally holding said levers in normal posture, said levers being efiective, conjointly, when rotated in a given direction about their common pivotal center to move said rocker member so as to increase the tension of the attached string, said second lever being effective when rotated individually about said pivotal center in said given direction to cause a rotation of said rocker member in a direction to slacken the tension of said string.

10. A tuning unit for a stringed musical instrument comprising: a first lever and a second lever having a common pivotal center, a rocker member pivotally mounted on and carried by said first lever, said rocker member being adapted for attachment to one end of a musical string, said second lever having means engaging said rocker member and effective when said levers are in normal posture to hold said rocker member against rotation under the tension of its atttached strin said levers normally extending in substantially parallel side-by-side relation from their common pivotal center, said levers being efiective, conjointly, when rotated in a given direction about their common pivotal center to move said rocker member so as to increase the tension of the attached string, said second lever being efiective when rotated individually about said pivotal center in said given direction to cause a rotation of said rocker member in a direction to slacken the tension of said string.

11. A tuning unit for a stringed musical instrument comprising: a first lever and a second lever having a common pivotal center, a rocker member pivotally mounted on and carried by said first lever, said rocker member being adapted for attachment to one end of a musical string, said second lever having means engaging said rocker member and effective when said levers are in normal posture to hold said rocker member against rotation under the tension of its attached string, said levers normally extending in substantially parallel side-by-side relation from their common pivotal center, a portion of said second lever underlying said first lever so that said second lever is rotatable by said first lever in one direction, said levers being efiective, conjointly, when rotated in said one direction about their common pivotal center to move said rocker member so as to increase the tension of the attached string,

said second lever being rotatable individually in said one direction and effective when so rotated to cause a rotation of said rocker member in a direction to slacken the tension of said string,

12. The combination in a stringed musical instrument, of a group of laterally spaced musical strings, means for anchoring said strings at one end of the group, a plurality of tuning units, one for each string, located adjacent the end of said group remote. from said anchoring means, each of said tuning units comprising a first lever, a second lever and a rocker member, said rocker member being pivotally mounted on and carried by said first lever and attached to one end of one of said strings, said second lever having means engaging said rocker member for normally holding said rocker member against rotation under the tension of the attached string, said levers having a common pivotal center and normally lying in substantially parallel side-by-side relation, said levers being operative, conjointly, when rotated in a given direction, to move said rocker member in a direction to increase the tension of said string, said second lever being operative when moved independently of said first lever and in said given direction from normal posture to rotate said rocker member to slacken the tension of said string, a cross-bar extending transversely of said tuning units and movable bodily toward and away from said units, and a plurality of pairs of actuating screws carried by said crossbar, one screw of each pair being operative, when suitably adjusted, to move both said levers in said given direction in response to a movement of said cross-bar, the other screw of each pair being operative, when suitably adjusted, to move said second lever in said given direction independently of said first lever in response to a like movement of said cross-bar.

13. A chord producing unit adapted for use with, and to form a part of, a stringed musical instrument of the type that embodies a substantially horizontal sounding board and has a plurality of parallel, spaced apart, tensioned strings a small distance above the board, said unit comprising a supporting structure mounted on the sounding board and provided with a pair of laterally spaced, upstanding side plates adjacent the strings, a crossbar extending transversely oi. the strings and between the side plates, provided with means between it and the supporting structure whereby it is mounted for limited vertical sliding movement in a truly rectilinear path and having associated therewith means whereby it may be operatively connected to any one or all of the strings in such manner that sliding movement thereof in one direction changes the tensioning of the strings to which it is operatively connected, pedal type means for sliding the crossbar in said one direction, and spring means between the supporting structure and the crossbar for urging said crossbar in the opposite direction.

J. D. HARLIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,234,874 Moore Mar. 11, 1941 2,235,718 Mafiei eta] Mar. 18, 1941 

